1. Field of the Invention
The present invention relates to a connection technique for a talkie device of a switchboard, and particularly to an apparatus and a method for a talkie connection between centrals (switchboards) when a network is constructed by plural switchboards.
2. Description of Related Art
When a connection between a calling terminal and a called terminal is made impossible due to some trouble in such a connection process that the calling terminal (caller) is connected to the called terminal (callee) through plural switchboards, there has been hitherto adopted a method that a switchboard causing the trouble acts to connect a talkie device i.e., a message generator, thereof to the calling terminal so that an audio is performed (e.g., a talkie guide message is played) to the calling terminal.
Specifically, as shown in FIG. 3A, when a telephone 4 serving as the calling terminal makes a dial calling to call (connect) another telephone which belongs to a switchboard 3, the telephone 4 transmits dial information through a switchboard 1, a line 5, a switchboard 2 and a line 6 to the switchboard 3. At this time, if the called telephone corresponding to the dial information does not exist in the switchboard 3, the switchboard 3 connects the line 6 to a vacant number talkie device 7 so that a message "the dialed number is not used at present" is output from the talkie device 7 to the calling telephone 4.
Furthermore, as shown in FIG. 3B, when the telephone 4 makes a dial calling to call a telephone 8 which belongs to the switchboard 3, if all the lines 6 between the switchboard 2 and the switchboard 3 are being used, the switchboard 2 connects the line 5 to a talkie device 9 which is used for such a situation that all lines are used (hereinafter referred to as "talkie device under all-used status"), so that a message "the line is crowed at present, and please call back later" is output from the talkie device 9 to the calling telephone 4.
In the conventional connection system using the talkie devices as described above, many lines between switchboards (i.e., centrals) are in use for a time when a caller hears a talkie guide message at the calling terminal side. Accordingly, even when another terminal needs one of the lines to make a call, the terminal encounters the all-used status at high probability.
Furthermore, when there occurs a cause to give a talkie guide to a calling terminal side during a process of connecting the calling terminal to a called terminal through plural switchboards and when all the talkie devices are being used (i.e., under all-used status) or no talkie device is provided, only a busy signal (sound) or a regulation sound is merely given to the calling terminal side, and no talkie guide is given to the calling terminal side. Therefore, the service quality for users is low.